JPH055099A - Electrically viscoelastic semi-solid substance - Google Patents

Abstract

PURPOSE:To provide an electrically viscoelastic semi-solid substance which comprises a gel produced by dispersing specific carbon powder in a partially cross-linked electrically insulating polymer, which changes its viscoelastic characteristics by the application of electric fields and which has extremely low fluidity. CONSTITUTION:An electrically viscoelastic semi-solid substance comprises an electrically responsible gel produced by dispersing (A) 20-70 pts.wt. of carbon powder having an average particle of 0.1-500mum and a carbon/hydrogen atomic ratio (C/H ratio) of 1.2-5 in (B) 80-30 pts.wt. of a partially cross-linked electrically insulating polymer having a penetration of >=40 at room temperature. The component A may be dispersed in an electrically insulating oil or polymer having a viscosity of >=500 centistokes at room temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electro-viscoelastic semi-solid whose viscoelastic property is changed by applying an electric field.

[0002]

2. Description of the Related Art Conventionally, an electrically controlled anti-vibration rubber or an electrically controlled damper in which an electrorheological fluid is enclosed can change the spring characteristic and loss characteristic by applying an electric field, and can cope with various input vibrations. Practical application is being considered as a part that can obtain excellent vibration damping and damping performance by changing the applied electric field. However, since an electrorheological fluid is a material that is highly fluid when no electric field is applied,
In order to function as an applied part, it was necessary to enclose it in another solid material such as rubber, metal or plastic.

In addition, an electric field-flexible polymer gel is known as a material capable of changing the viscoelasticity by applying an electric field. The electric field-flexible polymer gel is water, acetone or dimethyl sulfone. It only functions in solvents such as cyside, and application devices are limited to those that operate in such solvents.

[0004]

As described above, the viscoelastic characteristics can be changed by the electric field without the involvement of the electrorheological fluid having high fluidity and the liquid such as the polymer gel in the solvent. Functional materials have been desired. The present invention has been made to meet the above-mentioned demands, and an object of the present invention is to provide an electro-viscoelastic semi-solid capable of changing viscoelastic properties according to the strength of an applied electric field. ..

[0005]

Means for Solving the Problems As a result of intensive studies conducted by the present inventors in order to achieve the above object, as a result, in an electrorheological fluid, the viscosity of an electrically insulating oil, which is a dispersion medium, is remarkably increased, Focusing on the fact that the fluidity is remarkably reduced by partially crosslinking the medium, a semisolid non-conventional functional material capable of changing viscoelastic characteristics by applying an electric field was obtained, and the present invention was obtained. Has been completed.

The present inventors have found that the average particle size is 0.1 to 50.
A partially cross-linked electrically insulating polymer polymer having a penetration ratio of 40 or more at room temperature and 20 to 70 parts by weight of carbonaceous powder having a carbon / hydrogen atomic ratio (C / H ratio) of 1.2 to 5 at 0 μm. Electro-responsive gel characterized by being dispersed in 80 to 30 parts by weight of coalesce, or the above carbonaceous powder 20 to 7
0 parts by weight of electric insulating oil or electric insulating polymer 80 to 3 having a viscosity of 5000 centistokes or more at room temperature
An electrically responsive soft-plastic material characterized by being dispersed in 0 parts by weight is an electroviscoelastic semi-solid whose viscoelastic property can be changed by applying a voltage and which has extremely low fluidity. I found a thing.

The principle of function expression in the electro-responsive gel or electro-responsive soft-plastic material of the present invention is similar to the principle of electro-rheological fluid, and when an electric field is applied, carbon in the electro-insulating polymer is It is considered that the fine particles are polarized and an electrostatic force acts between the particles to generate an attractive force between the particles, and the viscoelastic property of the gel or the soft-plastic body changes while the particles are rearranged. The difference from the case of electrorheological fluid is that the viscosity of the dispersion medium is remarkably high, or the movement of particles is hindered by being cross-linked, and when an electric field is applied as in the case of electrorheological fluid, the particles move between the electrodes. It is thought that they will not be completely connected to each other in a beaded shape.

Therefore, what functions as a dispersed phase powder of an electrorheological fluid can be basically used as a powder to be filled in order to exhibit the function of the electroresponsive gel or electroresponsive soft-plastic material in the present invention. However, as pointed out in the case of electrorheological fluids, powders that function as the dispersed phase of so-called water-based electrorheological fluids, such as silica gel and lithium polyacrylate powder, in which water is essential for manifesting the function of electrorheological fluids. From the viewpoint of heat resistance and durability, the body is not preferable as the electrically responsive gel or the electrically responsive soft plastic body in the present invention.

From this point, the present inventors have found that the C / H ratio is 1.2 to 1.2, which is found as a suitable dispersed phase for a non-aqueous electrorheological fluid.
It has been found that 5, preferably 2 to 4 carbonaceous powders are also suitable for the electroresponsive gel or electroresponsive soft-plastic body according to the invention. When the C / H ratio is less than 1.2, the function of the electrically responsive gel or the electrically responsive soft-plastic material in the present invention is not exhibited, and when the C / H ratio exceeds 5, when an electric field is applied. Excessive current flows.

The particle size of the carbonaceous powder may be larger than that of the electrorheological fluid because there is no concern about sedimentation of the dispersed phase. The average particle size of the powder to be filled in order to exhibit the function of the electroresponsive gel or electroresponsive soft-plastic body is 0.1 to
500 μm is preferable, more preferably 1 to 100 μm.
m. When the average particle size of the powder particles exceeds 500 μm, it is difficult to disperse the particles uniformly in the dispersion medium, and the average particle size is 0.1 μm.
When it is less than the above, the function of the electroresponsive gel or the electroresponsive soft-plastic body becomes very small.

The carbon content of the carbonaceous powder is preferably 80 to 97% by weight, particularly preferably 90 to 95% by weight.
Is.

It is generally known that the volume resistivity of the dispersed phase of the electrorheological fluid is in the semiconductor region.
The volume resistivity of the carbonaceous powder changes depending on the ratio and the carbon content. That is, when the C / H ratio is low and the carbon content is low, the volume resistivity of the carbonaceous powder increases and becomes close to that of an insulator, and the electroviscoelastic effect in which the viscoelastic characteristics change in response to the application of an electric field does not appear. Further, if the C / H ratio is large and the carbon content is large, the conductivity is increased, but a large power consumption is required to exhibit the electroviscoelastic effect, which is not preferable. In this sense, the volume resistivity of the carbonaceous powder preferred in the present invention is 10 ⁵ to 10 ¹¹ Ω · cm, and more preferably 10
^{It is 7} to 10 ¹⁰ Ω · cm.

Specific examples of the carbonaceous powder suitable for the present invention include (1) finely pulverized coal tar pitch, petroleum pitch, or pitch obtained by thermally decomposing polyvinyl chloride, (2) Carbonaceous mesophase spherule powder obtained by heat-treating those pitches or their tar components, that is, powder obtained by dissolving pitch components with a solvent to separate optically anisotropic spherules formed by heating. Further, this was pulverized, and the pitch raw material was subjected to a heat treatment to form a bulk mesophase (see, for example, JP-A-59
-30887) and finely pulverized it, finely pulverized partially crystallized pitch, and (3) carbonized thermosetting resin at low temperature, such as carbonized phenolic resin micro beads. , So-called low temperature treated carbonaceous powder,
(4) Finely pulverized coals such as anthracite, bituminous coal and heat-treated products thereof, (5) Hydrocarbon-based vinyl polymers such as polyethylene, polypropylene or polystyrene and chlorine containing polyvinyl chloride or polyvinylidene chloride Examples thereof include carbon spheres obtained by heating a mixture with a polymer under pressure, finely pulverized carbon spheres, and (6) carbide of polyacrylonitrile. Among these,
Particularly preferred carbonaceous powders include carbonaceous mesophase microsphere powders and carbides of phenolic resin microbeads. Further, the carbonaceous powder may be subjected to various surface treatments for the purpose of increasing the dispersibility or reducing the current.

In the present invention, the dispersion medium in which the carbonaceous powder is dispersed is roughly classified into a partially crosslinked electrically insulating polymer and a non-crosslinked electrically insulating oil or electrically insulating polymer. However, when an electro-viscoelastic material in which carbonaceous powder is dispersed is used, a material that has a significantly low fluidity and becomes a semi-solid state is used.

The partially crosslinked electrically insulating high molecular polymer used in the electrically responsive gel or electrically responsive soft-plastic material of the present invention has a penetration value (consistency) of 40 (JIS) at room temperature. K2220) or above, preferably 50 to 20
0, more preferably 60 to 120, and having a volume resistivity of 10 ¹⁰ to 10 ¹⁷ , preferably 10 ¹² to 10 ¹⁷ , and more preferably 10 ¹⁴ to 10 ¹⁶ Ω · cm.

Specifically, partially crosslinked polydimethylsiloxane, partially crosslinked polymethylphenylsiloxane and other partially crosslinked silicone polymers, partially crosslinked polymethyltrifluoropropylsiloxane and other partially crosslinked fluorosilicone polymers, and partially crosslinked hydrocarbons. Examples of the polymers include partially crosslinked halogenated hydrocarbon polymers, partially crosslinked phosphazene polymers, and partially crosslinked urethane polymers. Among them, partially crosslinked gel-like silicones from the viewpoint of reliability and processability. Polymers are preferable, and particularly preferable examples include two-component or one-component silicone gel.

The electrically insulating oil or electrically insulating high molecular polymer used in the electrically responsive soft-plastic material of the present invention has a viscosity of 5000 centistokes or more, preferably 10 ⁴ to 1
0 ⁸ centistokes, more preferably 10 ⁴ to 10 ⁶
Centistokes, volume resistivity 10 ¹⁰ ~ 10 ¹⁷ Ω ·
cm, preferably 10 ¹² to 10 ¹⁷ Ω · cm, and more preferably 10 ¹³ to 10 ¹⁷ Ω · cm.

Specifically, silicone oils such as polydimethylsiloxane or polymethylphenylsiloxane, silicone polymers, fluorosilicone oils comprising polymethyltrifluoropropylsiloxane, hydrocarbon oils, hydrocarbon polymers, halogenated hydrocarbons. Examples thereof include oils, halogenated hydrocarbon polymers, phosphazene oils, and phosphazene polymers. Among them, silicone oils,
Silicone-based polymers and fluorosilicone oils are preferable, and polydimethylsiloxane oil, polymethyltrifluorosiloxane oil, and polydimethylsiloxane polymer are particularly preferable.

The ratio of the carbonaceous powder of the present invention to the dispersion medium is 20 to 70 parts by weight of the carbonaceous powder, preferably 40 to 60 parts by weight, and 30 to 80 parts by weight of the dispersion medium, preferably 60 to 4 parts.
When the proportion of the carbonaceous powder is less than 20 parts by weight, the viscoelastic change is small, and when it exceeds 70 parts by weight, the powder is difficult to disperse in the dispersion medium, which is not preferable.

Further, various additives such as a dispersant, a cross-linking agent and an antioxidant may be blended within a range that does not impair the effects of the present invention.

By providing a pair of electrodes in contact with the electroresponsive gel or electroresponsive soft-plastic material thus obtained and applying an electric field to the electrodes, the viscoelastic characteristics can be changed. .. When the storage elastic modulus G'when no electric field is applied is measured under the conditions of shear strain 10% and dynamic frequency 8 Hz, the material in the range of 10 ³ to 10 ⁵ dyne / cm ² has an increase of G'by voltage application. The degree is higher than the degree of increase of the loss elastic modulus G ″, and as a result, tan δ (G ″ / G ′) decreases. Meanwhile G '
When measured under the same conditions as above, the materials in the range of 10 ⁵ to 10 ⁶ dyne / cm ² have almost the same degree of increase in G ′ and G ″ due to voltage application, and tan δ does not change much. G ′ is 10 ⁶ dyne / cm ^2. For materials of cm ² or more, the increase in G ′ due to the voltage application is small, and only G ″ is increased, resulting in an increase in tan δ.

Hereinafter, the present invention will be described more specifically by way of examples. The present invention is not limited to the following examples.

Example 1 Coal tar was heat-treated in a substantially inert atmosphere at 450 ° C. using a 20 L (liter) autoclave, and the heat-treated product was extracted and filtered using tar-middle oil. .. The extraction / filtration residue was reheated at a temperature of 530 ° C. under a nitrogen stream of 2 L / min using a batch type rotary reactor having an internal volume of 2 L to obtain a carbonaceous powder. The average particle size of this carbonaceous powder is 18.8 μm,
The C / H ratio was 2.45 and the carbon content was 94.5% by weight.

50 parts by weight of this carbonaceous powder was added to 50 parts by weight of a two-component type silicone gel having a penetration of 80 at room temperature (SE1887 manufactured by Toray Dow Corning Silicone Co., volume resistivity: 4 × 10 ¹⁴ Ω · cm). Dispersion and heating at 80 ° C. for 1 hour gave an electrically responsive gel. About this electro-responsive gel, while applying a DC electric field at room temperature, a viscoelastic change (storage elastic modulus G ', loss elastic modulus G ", tan δ = G was measured using a RDS-II type viscoelasticity measuring device manufactured by Rheometry. "
/ G ') was measured. The fixture used has a radius of 1
The parallel plate was 2.5 mm, the shear strain was 10%, the dynamic frequency was 8 Hz, and the distance between the electrodes was 1.5 mm.
Table 1 shows the measurement results of the electroresponsive gel of Example 1.

[Table 1]

[Example 2] 50 parts by weight of carbonaceous powder similar to Example 1 was added to a two-pack type silicone gel having a penetration of 60 at room temperature (SE1890 manufactured by Toray Dow Corning Silicone Co., volume resistivity: 1x). 10 ¹⁵ Ω · cm) 50
It was dispersed in parts by weight and heated at 80 ° C. for 1 hour to obtain an electrically responsive gel. Table 2 shows the results of measuring the change in viscoelasticity of this electrically responsive gel in the same manner as in Example 1.

[Table 2]

Example 3 Coal tar was heat treated using a 20 L autoclave at 450 ° C. in a substantially inert atmosphere. The obtained heat-treated product was extracted and filtered using tar medium oil. Using a batch type rotary reactor with an internal volume of 2 L, the extraction / filtration residue was heated at a temperature of 500 ° C., 2 L /
The carbonaceous powder was obtained by reheating under a nitrogen stream for a minute and then pulverizing and classifying. This carbonaceous powder had an average particle size of 3.8 μm, a C / H ratio of 2.38, and a carbon content of 94.
It was 7% by weight.

50 parts by weight of this carbonaceous powder was dispersed in 50 parts by weight of a silicone gel having a penetration of 80 at the same room temperature as in Example 1 and heated at 80 ° C. for 1 hour to obtain an electrically responsive gel.
Table 3 shows the results of measuring the change in viscoelasticity of this electrically responsive gel in the same manner as in Example 1.

[Table 3]

[Example 4] 50 parts by weight of carbonaceous powder similar to that of Example 3 was dispersed in 50 parts by weight of silicone gel having a penetration of 60 at the same room temperature as in Example 2 and heated at 80 ° C for 1 hour to obtain an electrical response. A gel was obtained. Table 4 shows the results of measuring the change in viscoelasticity of this electrically responsive gel in the same manner as in Example 1.

[Table 4]

[Example 5] Commercially available phenol resin microbeads were heat-treated in a nitrogen stream at 600 ° C to give an average particle size of 8 µm, a C / H ratio of 2.28, and a carbon content of 91.4% by weight.
Of carbonaceous powder was obtained. 50 parts by weight of this carbonaceous powder was added to silicone gel 5 having a penetration of 60 at the same room temperature as in Example 2.
It was dispersed in 0 parts by weight and heated at 80 ° C. for 1 hour to obtain an electroresponsive gel. Table 5 shows the results of measuring the change in viscoelasticity of this electrically responsive gel in the same manner as in Example 1.

[Table 5]

Example 6 Fluorosilicone oil (FQF501 manufactured by Toshiba Silicone Co., Ltd.) made of polymethyltrifluoropropylsiloxane having a viscosity of 10,000 centistokes (cSt) at room temperature was used with 50 parts by weight of carbonaceous powder similar to that in Example 3. -1M, volume resistivity 3 × 10 ¹² Ω · c
m, dielectric constant 7.1) and dispersed in 50 parts by weight to obtain an electrically responsive soft plastic body. Table 6 shows the results of measuring the viscoelastic change of this electrically responsive soft-plastic material by the same method as in Example 1.

[Table 6]

[Example 7] 50 parts by weight of carbonaceous powder similar to that in Example 3 was added to a silicone oil made of polydimethylsiloxane having a viscosity of 10,000 centistokes (cSt) at room temperature (TSF451-1M manufactured by Toshiba Silicone Co., Ltd.,
A volume resistivity of 1 × 10 ¹⁴ Ω · cm) was dispersed in 50 parts by weight to obtain an electrically responsive soft plastic body. Table 7 shows the results of measuring the viscoelastic change of this electrically responsive soft-plastic material in the same manner as in Example 1.

[Table 7]

Example 8 50 parts by weight of the carbonaceous powder used in Example 1 was added to 50 parts by weight of polydimethylsiloxane polymer (SE30 manufactured by General Electric Co.) having a viscosity of 1.5 × 10 ⁶ centistokes (cSt) at room temperature. To obtain an electrically responsive soft plastic body. Table 8 shows the results of measuring the change in viscoelasticity of this electrically responsive soft-plastic material by the same method as in Example 1.

[Table 8]

[Comparative Example 1] Silicone oil (TSF451-10 manufactured by Toshiba Silicone Co.) consisting of 42.9 parts by weight of carbonaceous powder similar to that of Example 3 and composed of polydimethylsiloxane having a viscosity of 10 centistokes (cSt) at room temperature 5
Dispersion in 7.1 parts by weight gave an electrorheological fluid. Table 9 shows the results of measuring the viscoelastic change of this electrorheological fluid in the same manner as in Example 1.

[Table 9]

[Comparative Example 2] Silicone oil (TSF451-10 manufactured by Toshiba Silicone Co., Ltd.) made of polydimethylsiloxane having a viscosity of 1,000 centistokes (cSt) at room temperature was prepared by adding 20.7 parts by weight of carbonaceous powder similar to that of Example 3.
00) was dispersed in 79.3 parts by weight to obtain an electrorheological fluid.
Table 10 shows the results of measuring the viscoelastic change of this electrorheological fluid in the same manner as in Example 1.

[Table 10]

As shown in Tables 1-8, the electro-responsive gels or electro-responsive soft plastics of Examples 1-8 are viscous semi-solid substances having a storage elastic modulus G'even when no electric field is applied. Further, the storage elastic modulus G ′ and the loss elastic modulus G ″ are increased by applying an electric field. On the other hand, as shown in Tables 9 to 10, Comparative Example 1
In the electrorheological fluids of ~ 2, G'and G "increase by the application of an electric field, but the storage elastic modulus G'when no electric field is applied is almost 0, and the fluid is viscous and rich in fluidity. G'is 10 ³ to 10 ⁵ d as in Examples 1, 3, 4, 6, and 7.
For materials in the range of yne / cm ² , tan δ tends to decrease with voltage application. G'is 10 ⁵ to 10 as in Examples 2 and ^5.
For materials in the range of ⁶ dyne / cm ² , tan δ does not change much when a voltage is applied. As in Example 8, the material having G ′ of 10 ⁶ dyne / cm ² or more has an increased tan δ when a voltage is applied.

As described above, a functional material which can change its viscoelastic characteristics by applying an electric field while being semi-solid was obtained. As a result, the functions of the electrically controlled anti-vibration rubber, electrically controlled damper, etc., which have been conventionally obtained by enclosing the electrorheological fluid, use the solid state electrically responsive gel or electrically responsive soft plastic body of the present invention. By doing so, it is possible to simplify the structure of a component that can be obtained by forming a laminated structure with an electrode material instead of encapsulating and changing the vibration characteristics by electrical control.

[0037]

According to the present invention, a semi-solid functional material whose viscoelastic property can be changed by applying an electric field can be obtained, and the mechanical property can be changed by vibration control, electric control of a robot or the like. The structure of parts can be simplified.

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Claims (1)

Claims: 1. At room temperature, 20 to 70 parts by weight of carbonaceous powder having an average particle diameter of 0.1 to 500 µm and a carbon / hydrogen atomic ratio (C / H ratio) of 1.2 to 5 is used. An electroviscoelastic semi-solid comprising an electrically responsive gel dispersed in 80 to 30 parts by weight of a partially crosslinked electrically insulating polymer having a penetration of 40 or more. 2. 20 to 70 parts by weight of a carbonaceous powder having an average particle diameter of 0.1 to 500 μm and a carbon / hydrogen atomic ratio (C / H ratio) of 1.2 to 5 is added to a room temperature viscosity of 5000 centistokes or more. An electrically viscoelastic semi-solid comprising an electrically responsive soft-plastic material dispersed in 80 to 30 parts by weight of the electrically insulating oil or electrically insulating polymer.